58 Insight | UUVs possesses UUV-specific infrastructure for integrating, inspecting and testing AUVs, as well as dedicated waters for AUV operations for ad-hoc water trials without being restricted by maritime traffic control. While Hanwha Systems has previously developed four autonomous UUV platforms for defence tasks, and Hanwha Ocean has produced four successful crewed diesel-electric submarine solutions, neither has worked on an XLUUV before. Analysts anticipate the new contract, awarded in November 2023, was spurred by North Korea’s testing of its Haeil (Tsunami) nucleararmed UUV, earlier last year. Mine countermeasures Uncrewed systems can serve various naval functions, but mine countermeasures (MCM) are arguably the most important and most frequently touted for UUVs built with defence forces in mind – potentially because they can keep MCM crews as far away as possible from explosive hazards. In one of the latest developments for MCM UUVs, an L3Harris Iver4 900 AUV has been equipped with a Recon LS payload from Voyis Systems, as well as a Solstice 3000 multiple-aperture sonar (MAS) from Wavefront Systems. That AUV-payload combination has additionally passed factory acceptance testing and will be delivered to an undisclosed NATO member’s navy. Voyis’ Recon LS payload combines an underwater 3D Lidar (emitting a Class 3B laser with a wavelength of 448 nm and just under 75 mW of power) with either a 5 MP or 12 MP camera for precise 3D modelling. It has a scanning range of 1.2-7 m, depending on conditions, and it is depth-rated to a maximum of 1000 m. Wavefront’s MAS is designed to achieve scanning performance close to that of synthetic aperture sonar with the reliability and robustness of a conventional side-scan sonar. It does this through several techniques, including combining information from multiple transmission apertures and directions, using a proprietary processing format to improve signal-to-noise ratios. It also uses interferometric processing to accrue 3D bathymetric data, which includes information on the shapes and depth of underwater terrain, and is co-located with side-scan imagery. The Iver4 900 is a 2.5 m long, 23 cm diameter UUV, built from a combination of carbon composite and titanium, with a typical weight of 230 lb (104.3 kg). It can run on either a 2 kWh NiMH battery, which gives it 40 nm of range between battery recharges or swaps, or a 4 kWh Li-ion battery for a range of 80 nm. With the combined Recon LS and Solstice MAS payload, the AUV can detect, classify and identify mine-like objects (with the final step of identification usually depending on a diver or a remotely operated underwater vehicle), reducing false alarms and sustaining high tempo in MCM operations. Unique solutions In a further move towards accelerating defence AUV missions, L3Harris has successfully launched and recovered an AUV from an underway submarine’s torpedo tubes; a unique solution that the company calls its Torpedo Tube Launch and Recovery (TTL&R) technology. The process was performed autonomously, using a homing and docking solution integrated on to the torpedo tube, which an Iver4 900 AUV was able to propel from and to the host vehicle. The system has been designed in close collaboration with the US Navy, with a view towards ongoing development of hybrid crewed/uncrewed operational concepts, and potentially enabling every SSN-class submarine to serve as an AUV mothership. The Sabertooth UUV from Saab Seaeye (explored in detail in issue 36, February/March 2021) is another platform that is well-established in defence February/March 2024 | Uncrewed Systems Technology A Saab Sabertooth is being trialled by the US Navy to see how a hydrogen power plant could recharge UUVs without them needing to return to a ship or an onshore base (Image courtesy of Saab)
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